31 00 00: Earthwork

Earthworks conducted during site preparation and landscaping can significantly alter soil composition, hydrology, and vegetative cover, as well as introduce non-biodegradable erosion control and landscaping fabrics. In this division we look at less disruptive foundation options and biodegradable erosion control products.

Conventional foundation excavation can disturb plantings and soil, and cause sediment runoff and erosion, especially in fragile environments, such as boardwalks and decking in wetlands. Foundation options that reduce the need for excavation have a lower environmental impact, both onsite and globally, requiring less energy for transport of excavated material and fill. These foundation types often reduce the need for steel and concrete.

Natural-fiber biodegradable erosion control products perform well, and also serve as mulch to aid in seedling establishment as the site is landscaped.

Earthworks conducted during site preparation and landscaping can significantly alter soil composition, hydrology, and vegetative cover, as well as introduce non-biodegradable erosion control and landscaping fabrics. In this division we look at less disruptive foundation options and biodegradable erosion control products.

DeepRoot Green Infrastructure's impermeable geomembranes protect landscaping, hardscapes, and foundations against damage from underground water while also providing some protection against invasive species and roots. (For greater protection against roots, the company also makes dedicated root barrier products). DeepRoot’s geomembranes are made from a minimum 75% post-consumer recycled high-density polyethylene (HDPE) and are available in 300-foot rolls, in three thicknesses, and widths from 18" to 40".

SiltShield silt fencing is installed around job sites like traditional silt fencing, but is designed to be durable enough for reuse. The semi-rigid material includes drainage holes, to be set at or just above grade, and SiltShield's inner layer filters turbid runoff water.

Perma-Columns are precast concrete columns for post frame construction. Compared with a full concrete foundation, they reduce the need for concrete, while also setting aside the need for preservative-treated wood. Manufactured with rebar reinforcement and microfibers for durability, the 5' columns come in six dimensions to hold posts ranging from 4"x6" and 6"x6" to 4-ply 2"x8". Wood posts are bolted at the top of the column to a U-bracket of 1/4" domestic steel, which is welded to a steel reinforcement running the length of the column.

Postech’s thermal galvanized steel augered pile is insulated prevents ice build-up at the base of the pile. Postech foundations can be installed under existing structures, are reusable and adjustable, and are available with different blade dimensions for different soil types.

Geopier’s Rammed Aggregate Pier (RAP) systems are used to reinforce poor soils—such as sand, clay, silt, and peat—and support floor slabs and shallow foundations in commercial buildings as well as industrial tanks and embankments. Using a RAP system can significantly reduce the environmental impact caused by removing unstable soil and replacing it with engineered fill. The company’s RAP system consists of auguring 30-inch-diameter shafts 7 to 30 feet deep, filling them with crushed rock in small batches, and compacting the aggregate using a specially designed hydraulic hammer. The ram’s angled shape forces the aggregate down and laterally to compact and stabilize the surrounding soil. According to the company, the RAP system has supported foundation loads exceeding 4,000 kips (4-million pounds force per square foot) with less than one inch of settling.

Curlex® NetFree™ is a 100% biodegradable excelsior erosion control blanket made with softly barbed, interlocking, curled, Great Lakes Aspen excelsior wood fibers (80% over 6” long) stitched together with biodegradable thread. These blankets are free from weed seed, chemical additives, tackifiers, and paper products. The netless blankets will not entrap wildlife or pets, tangle in mowing equipment, present future environmental risk, or trip pedestrians. Available in 8’ wide X 90’ long rolls (80 sq. yards), NetFree can be used in low-flow channels up to 1-lb/ft2 shear stress and is recommended for 3:1 maximum slopes. American Excelsior Company has 10 locations in the U.S. and over 100 distributor partners.

North American Green offers 100% biodegradable (as opposed to photodegradable) rolled erosion control blankets, including the netting and thread. The woven net structure reduces the risk of wildlife entrapment and prevents fiber loss. Matrices are agricultural straw or a combination of straw and coir (coconut fiber). Products are available to meet specific applications and functional longevities. 6.7’ x 108’ rolls cover 80 yd². North American Green also offers erosion control blankets made with photodegradable polypropylene netting, and blanket pins made of biodegradable PLA plastic. North American Green is a wholly-owned, stand-alone subsidiary of Tensar International Corporation with headquarters in Atlanta, Ga.

Nedia Enterprises manufactures a full line of primarily coir-based erosion control products. KoirMat™ erosion control matting, made from 100% coir fiber, is available in 39%, 50%, or 65% openness for a wide variety of applications. KoirLog™ is a 100% coconut fiber "log" for shoreline and stream channel erosion control applications. KoirLog is available in 12", 16", and 20" diameters and is typically 10' to 20' long.

A. B. Chance manufactures the Instant Foundation®, a unique screw-anchor foundation system for supporting walkways in ecologically sensitive areas. The steel piers are screwed into the ground or wetland using portable rotary augering equipment, eliminating the need for any excavation or concrete. A. B. Chance also manufactures galvanized-steel hardware to complete the installations.

RoLanka manufactures a full line of coir-based products for soil erosion control, sediment control, and streambank stabilization. BioD-Mat semi-permanent mats last 4–6 years and are available from 38% to 65% openness, with the BioD-Mat 90 made to withstand up to 16 ft/s of water runoff.

Diamond Pier™ DP-100 and DP-50 permit installation of pier foundations with neither excavation nor site-poured concrete. These products provide structural foundation systems for decks, outbuildings, and boardwalks. Held in place with four steel pins driven at angles through the piers and deep into the ground, they are particularly appropriate for frost conditions, fragile ecosystems, heaving soils, or difficult access sites. The company's Butterfly™ and Speed Pile™ systems are no longer offered.

Belton offers a range of jute and coir products. Geojute is available in four products of varying weight and openness; its signature line, Anti-wash/Geojute, is woven in a 1/2" grid pattern that is suitable for moderate slopes, sustaining runoff velocities of up to 8 ft/s. The jute fabric, available in 4'-wide by 225'-long rolls, biodegrades in one to two years. Geocoir is stronger and more durable than jute geotextiles. This product is available in three different weights—400, 700, and 900 g/m2—as well as a stabilization fencing system and coir logs. Geocoir is typically used on steeper slopes, and may last from 4 to 5 years depending upon the application.

Slopetame2 is a plastic grid product made from 100% injection-molded recycled HDPE with varying amounts of post-consumer and post-industrial content. Slopetame2 is designed to provide immediate erosion control in permanent installations on weak or eroding slopes by resisting undercutting water and soil movement. It has a geotextile backing.